Methods for bottom up fin structure formation

ABSTRACT

Embodiments described herein relate to substrate processing methods. The methods include forming a patterned hardmask material on a substrate, forming first mandrel structures on exposed regions of the substrate, and depositing a gap fill material on the substrate over the hardmask material and the first mandrel structures. The first mandrel structures are removed to expose second regions of the substrate and form second mandrel structures comprising the hardmask material and the gap fill material. Fin structures are deposited on the substrate using the second mandrel structures as a mask.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims benefit to U.S. patentapplication Ser. No. 15/896,839, filed Feb. 14, 2018, the entirety ofwhich is herein incorporated by reference.

BACKGROUND Field

Embodiments of the present disclosure generally relate to methods forbottom up fin structure formation.

Description of the Related Art

Fin field effect transistors (FinFETs) are structures commonly utilizedin the fabrication of semiconductor devices. Conventional FinFETs atcurrent technology nodes are fabricated with conventional etchingtechniques. However, at advanced technology nodes with reduced criticaldimensions and increasing aspect ratios, conventional etching techniquesare inadequate to fabricate defect free FinFET devices.

For example, in order to fabricate FinFET devices with sufficientverticality for utilization in various semiconductor devices, thickspacers are utilized to pattern an underlying hardmask. The thick spacerheight is utilized to reduce bending or leaning of the patterned spacer.However, when the spacer pattern is transferred to the hardmask, lessthan desirable verticality of the hardmask may persist which results inFinFET devices with slanted sidewalls or occluded trenches betweenadjacent FinFET structures.

Thus, what is needed in the art are improved methods for fin structureformation.

SUMMARY

In one embodiment, a substrate processing method is provided. The methodincludes forming a patterned hardmask material on a substrate, formingfirst mandrel structures on exposed regions of the substrate, anddepositing gap fill material on the hardmask material and the firstmandrel structures. The method also includes removing the first mandrelstructure to expose second regions of the substrate and form secondmandrel structures comprising the hardmask material and the gap fillmaterial and forming fin structures on the second regions of thesubstrate using the second mandrel structures as a mask.

In another embodiment, a substrate processing method is provided. Themethod includes forming a hardmask material on a substrate, depositing aspacer material on the hardmask material, patterning the spacermaterial, and transferring the pattern of the spacer material to thehardmask material by etching the hardmask material to expose regions ofthe substrate. First mandrel structures are formed on the exposedregions of the substrate. A gap fill material is deposited on thehardmask material and the first mandrel structures. The first mandrelstructures are removed to expose second regions of the substrate andform second mandrel structures comprising the hardmask material and thegap fill material. Fin structures are formed on the second regions ofthe substrate using the second mandrel structures as a mask, andrecessing the gap fill material below a top surface of the finstructures.

In yet another embodiment, a substrate processing method is provided.The method includes forming a patterned hardmask material on a substrateand forming III-V material first mandrel structures on exposed region ofthe substrate. The III-V material first mandrel structures extend afirst distance of greater than about 80 nm above a top surface of thesubstrate. A flowable oxide gap fill material is deposited on thehardmask material and the III-V material first mandrel structures. TheIII-V material first mandrel structure are removed to expose secondregions of the substrate and form second mandrel structures comprisingthe hardmask material and the flowable oxide gap fill material. Thesecond mandrel structures extend a second distance above the top surfaceof the substrate that is approximately equal to the first distance. Finstructures are epitaxially deposited on the second regions of thesubstrate and the gap fill material is etched after forming the finstructures.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, and may admit to other equally effective embodiments.

FIG. 1 illustrates a partial cross-sectional view of a substrate havinga patterned spacer material and hardmask material formed thereonaccording to an embodiment described herein.

FIG. 2 illustrates a partial cross-sectional view of the substrate ofFIG. 1 with the spacer material removed and first mandrel structuresformed on the substrate according to an embodiment described herein.

FIG. 3 illustrates a partial cross-sectional view of the substrate ofFIG. 2 with a gap fill material formed on the substrate over thehardmask material and the first mandrel structures according to anembodiment described herein.

FIG. 4 illustrates a partial cross-sectional view of the substrate ofFIG. 3 after planarization of the gap fill material according to anembodiment described herein.

FIG. 5 illustrates a partial cross-sectional view of the substrate ofFIG. 4 with the first mandrel structures removed to form second mandrelstructures according to an embodiment described herein.

FIG. 6 illustrates a partial cross-sectional view of the substrate ofFIG. 5 after forming fin structures on the substrate according to anembodiment described herein.

FIG. 7 illustrates a partial cross-sectional view of the substrate ofFIG. 6 after etching the gap fill material according to an embodimentdescribed herein.

FIG. 8 illustrates operations of a method for patterning and etching asubstrate according to an embodiment described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments described herein relate to substrate processing methods thatadvantageously form fin structures form the bottom up. The methodsinclude forming a patterned hardmask material on a substrate, formingfirst mandrel structures on exposed regions of the substrate, anddepositing a gap fill material on the substrate over the hardmaskmaterial and the first mandrel structures. The first mandrel structuresare removed to expose second regions of the substrate and form secondmandrel structures comprising the hardmask material and the gap fillmaterial. Fin structures are deposited on the substrate using the secondmandrel structures as a mask.

FIG. 8 illustrates a flow diagram of a method 800 for bottom uppatterning and etching a substrate according to an embodiment describedherein. The method 800 is discussed concurrently with the illustrationsdepicted in FIGS. 1-6. At operation 810, a spacer material is patternedand the pattern is transferred to an underlying hardmask material.

FIG. 1 illustrates a partial cross-sectional view of a substrate 102having a patterned spacer material 106 and a hardmask material 104formed thereon according to an embodiment described herein. In oneembodiment, the substrate 102 is fabricated from a semiconductingmaterial, such as silicon. For example, the substrate 102 is amonocrystalline silicon material which is either an intrinsic (un-doped)silicon material or an extrinsic (doped) silicon material. If anextrinsic silicon material is utilized, the dopant may be a p-typedopant, such as boron. In another embodiment, the substrate 102 is asilicon-on-insulator substrate.

As illustrated in FIG. 1, the spacer material 106 and the hardmaskmaterial 104 are patterned. Prior to patterning, the hardmask material104 is deposited on and in contact with the substrate 102 in a blankettype layer. The spacer material 106 is then deposited on and in contactwith the hardmask material 104. Patterning of the spacer material 106 isperformed by various processes suitable for advanced technology nodes,such as the 10 nm node, the 7 nm node, the 5 nm node, and beyond.Examples of suitable patterning processes include self-aligned doublepatterning and self-aligned quadruple patterning which are, dependingupon the desired implementation, immersion lithography or extremeultraviolet (EUV) lithography processes. Other suitable patterningprocesses include directed self-assembly, 193 nm immersionlitho-etch-litho-etch (LELE), and EUV LELE, among others.

The patterned spacer material 106 creates a mask for subsequent etchingof the underlying hardmask material 104. In one embodiment, the spacermaterial 106 is a silicon oxide material, a silicon nitride material, ora titanium oxide material. In one embodiment, a thickness of thepatterned spacer material 106 is approximately equal to one half of thefin pitch. For example, the thickness of the patterned spacer materialis between about 15 nm and about 20 nm. In one embodiment, a thicknessof the hardmask material 104 is between about 30 nm and about 50 nm,such as about 40 nm. The hardmask material 104 is fabricated from asilicon oxide material in one embodiment and a silicon nitride materialin another embodiment.

An etching process, such as a wet etching process or dry etchingprocess, is utilized to etch the hardmask material 104, thustransferring the pattern from the spacer material 106 to the hardmaskmaterial. In one embodiment, the etching process is a dry etchingprocess. In this embodiment, a nitride or oxide containing film isetched with a fluorine containing plasma generated from one or more ofthe following precursors: CF₄, CHF₃, CH₂F₂, CH₃F, O₄F₆, or C₄F₈. Asource power utilized to generate the plasma is between about 300 W andabout 1500 W, a bias power utilized to bias the plasma is between about50 W and about 700 W, a pressure of a process environment for performingthe etching process is maintained between about 5 mTorr and about 20mTorr, and a temperature of the substrate 102 during the etching processis maintained between about 10° C. and about 80° C. After etching of thehardmask material 104, regions 114 of the substrate 102 are exposedbetween adjacent portions of the hardmask material 104.

A pitch 108 of the patterned hardmask 106 is less than about 40 nm, suchas about 30 nm or less. In this embodiment, a width 110 of certainhardmask material portions is about 20 nm or less, such as about 15 nmor less. Similarly, a width 112 of the exposed regions 114 is about 20nm or less, such as about 15 nm or less.

At operation 820, first mandrel structures 202 are formed on a substratepatterned by the hardmask material 104. FIG. 2 illustrates a partialcross-sectional view of the substrate of FIG. 1 with the spacer material106 removed and first mandrel structures 202 formed on the substrate 102according to an embodiment described herein. The spacer material 106 isremoved by suitable selective etching processes, such as wet etching ordrying etching processes.

In embodiments where the spacer material 106 is a silicon oxidematerial, a plasma is generated from one or more of the followingprecursors: C₄F₆, O₂, Ar, and He. In this embodiment, a source powerutilized to generate the plasma is between about 300 W and about 900 W,a bias power utilized to bias the plasma is between about 300 W andabout 700 W, and a pressure of a process environment for performing theetching process is maintained between about 5 mTorr and about 15 mTorr.In embodiments where the spacer material 106 is a silicon nitridematerial, a plasma is generated from one or more of the followingprecursors: CH₃F, CH₄, O₂, H₂, N₂, and He. In this embodiment, a sourcepower utilized to generate the plasma is between about 400 W and about800 W and a bias power utilized to bias the plasma is between about 30 Wand about 100 W. In other embodiments where the spacer material 106 is asilicon oxide material, a dilute HF wet etching process is utilized.

In one embodiment, suitable apparatus for performing the etching processis the CENTRIS™ SYM3™ etching apparatus available from AppliedMaterials, Inc., Santa Clara, Calif. It is contemplated that othersuitably configured apparatus from other manufacturers may also beutilized in accordance with the embodiments described herein. The spacerremoval process removes the spacer material 106 selectively to thehardmask material 104 and the substrate 102, leaving the hardmaskmaterial 104 on the substrate 102.

The first mandrel structures 202 are formed in the exposed regions 114depicted in FIG. 1. The first mandrel structures 202 are deposited on asurface 206 of the substrate and the first mandrel structures 202 grownfrom the surface 206 of the substrate 102. In one embodiment, a suitableapparatus for performing the first mandrel structure deposition is theCENTURA® RP EPI apparatus available from Applied Materials, Inc., SantaClara, Calif. It is contemplated that other suitably configuredapparatus from other manufacturers may also be utilized in accordancewith the embodiments described herein. Each of the first mandrelstructures 202 are separated from adjacent first mandrel structures 202by the patterned hardmask material 104 and spacers 210. The firstmandrel structures 202 are grown such that a top surface 208 of thefirst mandrel structures 202 is a distance 204 of greater than about 80nm above the surface 206 of the substrate 102. In one embodiment, thedistance 204 is between about 100 nm and about 200 nm.

In one embodiment, the first mandrel structures 202 are formed on thesubstrate 102 by an epitaxial deposition process. In one embodiment, agallium containing precursor and an arsenic containing precursor arepulsed in an alternating matter to deposit the first mandrel structures202. In this embodiment, the gallium containing precursor istrimethylgallium and the arsenic containing precursor is AsH₃. In thisembodiment, the first mandrel structures 202 are fabricated in anenvironment maintained at a pressure of between about 1 Torr and about10 Torr and a temperature of between about 450° C. and about 800° C. Theepitaxial deposition process utilizes a layer-by-layer depositiontechnique which is believed to maintain the substantially verticalorientation of the first mandrel structures 202 as the first mandrelstructures 202 continue to grow from the surface 206 and above thehardmask material 104.

In one embodiment, the first mandrel structures 202 are formed from aIII-V material. For example, the first mandrel structures 202 are formedfrom one or more of aluminum antimonide, aluminum arsenide, aluminumgallium arsenide, aluminum gallium indium phosphide, aluminum galliumnitride, aluminum gallium phosphide, aluminum indium arsenide, aluminumnitride, aluminum phosphide, boron arsenide, boron nitride, boronphosphide, gallium antimonide, gallium arsenide, gallium arsenidephosphide, gallium phosphide, indium antimonide, indium arsenide, indiumgallium arsenide, indium gallium nitride, indium gallium phosphide,indium nitride, and indium phosphide, among others.

At operation 830, the gap fill material 302 is deposited on thesubstrate 102 over the hardmask material 104 and the first mandrelstructures 202. FIG. 3 illustrates a partial cross-sectional view of thesubstrate 102 of FIG. 2 with a gap fill material 302 formed on thesubstrate 102 over the hardmask material 104 and the first mandrelstructures 202 according to an embodiment described herein. The gap fillmaterial 302 is deposited such that the gap fill material fills thevoids 210 and is deposited to a thickness beyond the top surface 208 ofthe first mandrel structures 202. In one embodiment, a suitableapparatus for performing the gap fill deposition process is thePRODUCER® ETERNA™ FCVD™ apparatus available from Applied Materials,Inc., Santa Clara, Calif. It is contemplated that suitably configuredapparatus from other manufacturers may also be utilized in accordancewith the embodiments described herein.

In one embodiment, the gap fill material is a flowable material. Theflowable material has characteristics of a solid material but also hasthe ability to “flow,” thus enabling substantially void-free bottom upmaterial deposition. In one embodiment, the gap fill material 302 isdeposited by a flowable chemical vapor deposition (CVD) process. In oneexample, a CVD process is utilized to deposit a flowable silicon oxidecontaining gap fill material 302. In this embodiment, a silicon oxidematerial is sequentially deposited, cured, and annealed. In anotherexample, a CVD process is utilized to deposit a silicon nitride gap fillmaterial 302. In this embodiment, a silicon nitride material issequentially deposited and subjected to a nitridation plasma treatment.In another embodiment, the gap fill material 302 is formed by a spin onglass (SOG) process. In this embodiment, the gap fill material 302 is anoxide containing material, such as silicon dioxide or the like.

At operation 840, the gap fill material is planarized. FIG. 4illustrates a partial cross-sectional view of the substrate 102 of FIG.3 after planarization of the gap fill material 302 according to anembodiment described herein. In one embodiment, planarization of the gapfill material 302 is performed by a chemical mechanical polishingprocess. In another embodiment, planarization of the gap fill material302 is performed by an etching process.

The gap fill material 302 is removed to a point where a top surface 402of the gap fill material 302 is substantially planar with the topsurface 208 of the first mandrel structures 202. In one embodiment, itis contemplated that the first mandrel structures 202 are utilized as aremoval point. In another embodiment, the gap fill material 302 issubjected to a time based etching process to planarize the surfaces 402,208.

At operation 850, the first mandrel structures 202 are removed to formthe second mandrel structures 500 which include the hardmask material104 and the gap fill material 302. FIG. 5 illustrates a partialcross-sectional view of the substrate 102 of FIG. 4 with the firstmandrel structures 202 removed to form second mandrel structures 500according to an embodiment described herein. A selective etching processis utilized to remove the first mandrel structures 202. For example,etch chemistries selective to III-V materials are utilized to remove thefirst mandrel structures 202 selectively to the oxide and/or nitridecontaining gap fill material 302 and hardmask material 104.

In one embodiment, a chlorine containing precursor, such as HCl, isdelivered to a process environment with a hydrogen containing precursor,such as H₂. The precursors are delivered to the process environment withan inert carrier gas such as N₂ or Ar. In one example, the HCl isdelivered to the process environment at a flow rate of between about 1sccm and about 500 sccm. A temperature of the process environment ismaintained between about 300° C. and about 700° C. and a pressure of theprocess environment is maintained between about 0 Torr and about 100Torr.

Removal of the first mandrel structures 202 results in spaces 502 formedbetween adjacent second mandrel structures 500. The spaces 502 alsoexpose a second region of the top surface 206 of the substrate 102. Aheight of the second mandrel structures 500 is similar to the distance204, for example, substantially equal to the distance 204.

At operation 860, the fin structures 602 are deposited on the substrate102 using the second mandrel structures 500 as a mask. FIG. 6illustrates a partial cross-sectional view of the substrate 102 of FIG.5 after forming fin structures 602 on the substrate 102 according to anembodiment described herein. The fin structures 602 extend a seconddistance 606 of greater than about 80 nm, such as between about 100 nmand about 200 nm, above the surface 206. In one embodiment, the finstructures 602 are formed by an epitaxial deposition process. In thisembodiment, the material utilized to form the fin structures 602 are thesame as the material utilized to form the substrate 102. In otherembodiments, the materials utilized to form the fin structures includesilicon containing materials, germanium containing materials, silicongermanium containing material, and III-V materials, among others. Forexample, a dichlorosilane precursor and a GeH₄ precursor are activatedand pulsed in an alternating manner to deposit a silicon germaniummaterial as the fin structures 602.

The fin structures 602 extend the second distance 606 such that a topsurface 604 of the fin structures 602 are substantially co-planar withthe top surface 402 of the gap fill material 302. By utilizing thesecond mandrel structures 500 as a mask or mold/confinement structure,it is believed that the fin structures 602 exhibit an improvedverticality profile due to the improved verticality of the hardmaskmaterial 104 and the gap fill material 302 of the second mandrelstructures 500. The second mandrel structures 500 are also believed toreduce lateral growth of the fin structures 602 during formation and mayalso reduce undesirable facet formation within the fin structures 602.

At operation 870, the gap fill material 302 of the second mandrelstructures 500 is etched to expose the fin structures 602. FIG. 7illustrates a partial cross-sectional view of the substrate 102 of FIG.6 after etching the gap fill material 302 according to an embodimentdescribed herein. In one embodiment, the top surface 402 of the gap fillmaterial 302 is recessed from the top surface 604 of the fin structuresa third distance 704 of greater than about 80 nm, such as between about100 nm and about 200 nm. The gap fill material 302 is etched by aselective etching process that preferentially etches to the oxide ornitride materials of the gap fill material 302. In one embodiment, aSICONI® process, available from Applied Materials, Inc., Santa Clara,Calif., is utilized to etch the gap fill material 302.

After recessing the gap fill material 302 to expose the fin structures602, subsequent semiconductor processing operations may be performed. Itis contemplated that the remaining portion of second mandrel structures500 may remain disposed on the substrate 102 to provide for finisolation or may be removed, depending upon the desired deviceimplementation.

In summation, improved mask formation and etching process flows providefor bottom up fin formation for the fabrication of advancedsemiconductor devices. By reducing spacer material height and byincreasing the mask height (i.e. first and second mandrel structures),improved etching verticality may be achieved. It is also believed thatby utilizing the process flows described herein, sidewall verticality ofthe masks (first and second mandrel structures) may be improved, whichresults in desirable etching verticality characteristics. Accordingly,sidewall (lateral growth) is more effectively controlled and edgeroughness is also reduced.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A substrate processing method, comprising:forming first mandrel structures on exposed first regions of asubstrate; depositing a gap fill material over the first mandrelstructures; removing the first mandrel structures to expose secondregions of the substrate and form second mandrel structures comprisingthe gap fill material; and forming fin structures on the second regionsof the substrate.
 2. The method of claim 1, wherein the first mandrelstructures are formed in an environment maintained at a pressure ofbetween about 1 Torr and about 10 Torr.
 3. The method of claim 1,wherein the first mandrel structure are formed at a temperature ofbetween about 450° C. and about 800° C.
 4. The method of claim 1,further comprising: etching the gap fill material after forming the finstructures.
 5. The method of claim 1, wherein the forming the finstructures comprises epitaxially depositing on the second regions of thesubstrate a material selected from the group consisting of siliconcontaining material, germanium containing material, silicon germaniumcontaining materials, and III-V materials.
 6. The method of claim 1,further comprising: performing a chemical mechanical polishing processto planarize the gap fill material prior to removing the first mandrelstructures.
 7. The method of claim 1, further comprising: performing anetching process to planarize the gap fill material prior to removing thefirst mandrel structures.
 8. The method of claim 1, wherein the firstmandrel structures are formed by an epitaxial deposition process.
 9. Themethod of claim 8, wherein the first mandrel structures comprise a III-Vmaterial.
 10. The method of claim 1, wherein depositing the gap fillmaterial comprises performing a chemical vapor deposition process. 11.The method of claim 10, wherein performing the chemical vapor depositionprocess comprises depositing a flowable silicon oxide material or aflowable silicon nitride material.
 12. The method of claim 11, whereinthe depositing a flowable silicon oxide material comprises: curing theflowable silicon oxide material; and annealing the flowable siliconoxide material.
 13. The method of claim 11, wherein the depositing aflowable silicon nitride material comprises exposing the flowablesilicon nitride material to a nitridation plasma treatment.
 14. Themethod of claim 1, wherein depositing the gap fill material comprisesdepositing an oxide containing material deposited by a spin on glassprocess.
 15. The method of claim 1, further comprising: depositing ahardmask material on the substrate; and depositing a spacer material onthe hardmask material.
 16. A substrate processing method, comprising:forming first mandrel structures on exposed regions of a substrate;depositing a gap fill material over the first mandrel structures;removing the first mandrel structures to expose second regions of thesubstrate and form second mandrel structures comprising the gap fillmaterial; forming fin structures on the second regions using the secondmandrel structures as a mask; and recessing the gap fill material belowa top surface of the fin structures.
 17. The method of claim 16, whereinthe fin structures are formed by an epitaxial deposition process. 18.The method of claim 16, wherein the fin structures are formed from amaterial selected from the group consisting of silicon containingmaterial, germanium containing material, silicon germanium containingmaterials, and III-V materials.
 19. The method of claim 16, wherein thefirst mandrel structures are formed at a pressure of between about 1Torr and about 10 Torr and a temperature of between about 450° C. andabout 800° C.
 20. A substrate processing method, comprising: forming apatterned hardmask material on a substrate; forming first mandrelstructures on exposed regions of the substrate, wherein the firstmandrel structures extend above a top surface of the substrate;depositing a gap fill material over the hardmask material and the firstmandrel structures; removing the first mandrel structures to exposesecond regions of the substrate and form second mandrel structurescomprising the hardmask material and the flowable oxide gap fillmaterial, wherein the second mandrel structures extend a second distanceabove the top surface of the substrate; depositing fin structures on thesecond regions of the substrate; and planarizing the gap fill materialafter forming the fin structures.